Читать книгу Kinematics of General Spatial Mechanical Systems - M. Kemal Ozgoren - Страница 16

Two vectors and are defined to be equal, i.e. , if they satisfy the following equations simultaneously, in which .

(1.6)

(1.7)

In Eqs. (1.6) and (1.7), σ is a sign variable such that

(1.8)

In Eq. (1.7), the notation indicates the direction of the vector . Equation (1.7) implies the following two situations for the unit vectors and .

If σ = + 1, and are codirectional, i.e. either coincident or parallel with the same direction.

If σ = − 1, and are opposite, i.e. either coincident or parallel with opposite directions.